Machine to machine (Machine to Machine, M2M), that is an Internet of things technology connects all things to the Internet through an information sensing device, so as to implement intelligent identification and management. A conventional M2M device is tightly combined with a wireless communications technology, so that an M2M technology has diversified applications, and when the M2M is applied to a mobile communication system, it is a machine type communication (Machine Type Communication, MTC).
Referring to FIG. 1, a specific MTC application system includes a third generation partnership project (3rd Generation Partnership Project, 3GPP) internal network and a 3GPP external network, and the 3GPP external network includes a plurality of MTC users (User) and corresponding MTC servers (server), where each MTC user is corresponding to one MTC server, and provides various MTC services for a client through communications with the corresponding MTC server, such as a vending machine service and a wireless water-electricity management service. An MTC device (device), that is, a terminal device is capable of accessing an MTC server from a 3GPP network and communicating with the MTC server, so as to receive a service provided by the MTC server.
In the conventional MTC application system, each MTC server may directly access a plurality of fixed network elements in the 3GPP network, so that the network elements in the 3GPP network are insecure.